Sky at a Glance | June 25th, 2010

June 26th's lunar eclipse
The northern half of the Moon skims through Earth’s umbra (dark shadow core) on Saturday morning, June 26th. Less noticeable will be the first and last stages of the eclipse, when the Moon is in the penumbra, the shadow’s pale outer fringe. See article.
Sky & Telescope illustration

Friday, June 25

  • Full Moon tonight. A partial eclipse of the Moon happens in the early hours of Saturday morning for the western half of the United States. The Moon, in Sagittarius, will be sinking low in the southwest as dawn approaches. See our article, Saturday's Predawn Lunar Eclipse.

    Saturday, June 26

  • As evening grows late, the low Moon shines left of the Sagittarius Teapot.

    Sunday, June 27

  • The big Summer Triangle is rising up the eastern sky. Vega, the brightest star in the east, is its topmost corner. Lower left of Vega is Deneb, and farther lower right of Vega is Altair. Look for little Delphinus, the Dolphin, already appearing to Altair's lower left.

    Monday, June 28

  • At this time of year the Little Dipper floats straight upward from Polaris after dark, like a helium balloon on a string escaped from a summer evening party.

    Tuesday, June 29

  • A small telescope will show Titan, the largest moon of Saturn, four ring-lengths to Saturn's east this evening and tomorrow evening.

    Wednesday, June 30

  • The asteroid 1 Ceres is now in Ophiuchus and is still as bright as magnitude 7.3. Spot it with binoculars or a small scope using our article and finder chart: Ceres in 2010.

    Thursday, July 1

  • July is Scorpius season! This loveliest of summer constellations is now well up in the south-southeast as early as nightfall. Take a tour of telescopic sights in and around this rich region using Sue French's Deep-Sky Wonders column and charts in the June Sky & Telescope, page 65.

    Twilight view westward
    Action is happening in the western twilight lineup. Watch Venus close in on Regulus day by day, while Mars closes in on Saturn.

    Friday, July 2

  • The waning Moon rises around midnight tonight (depending on where you live in your time zone). About 45 minutes later, up comes Jupiter beneath it.

    Saturday, July 3

  • As night falls at this time of year, Arcturus is high in the southwest straight above Spica (depending on your latitude). And the kite shape of Bootes extends straight up from Arcturus.


    Want to become a better amateur astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.

    Sky Atlas 2000.0 (the color Deluxe Edition is shown here) plots 81,312 stars to magnitude 8.5. That includes most of the stars that you can see in a good finderscope, and typically one or two stars that will fall within a 50× telescope's field of view wherever you point. About 2,700 deep-sky objects to hunt are plotted among the stars.
    Alan MacRobert

    For an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential magazine of astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).

    Once you get a telescope, to put it to good use you must have a detailed, large-scale sky atlas (set of charts). The standards are the Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger Sky Atlas 2000.0 (stars to magnitude 8.5); and the even larger and deeper Uranometria 2000.0 (stars to magnitude 9.75). And read how to use your charts effectively.

    You'll also want a good deep-sky guidebook, such as Sky Atlas 2000.0 Companion by Strong and Sinnott, or the more detailed and descriptive Night Sky Observer's Guide by Kepple and Sanner, or the classic if dated Burnham's Celestial Handbook.

    Can a computerized telescope take their place? I don't think so — not for beginners, anyway, and especially not on mounts that are less than top-quality mechanically. As Terence Dickinson and Alan Dyer say in their Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."


    This Week's Planet Roundup

    Mercury is hidden in the glare of the Sun.

    Venus (magnitude –4.0, moving from Cancer into Leo) is the bright Evening Star sinking low in the west as twilight fades. In a telescope Venus is still a small (15-arcsecond) gibbous disk. You'll have the cleanest telescopic views of it when it's higher in the blue sky of afternoon — if you can find it then. Not until late summer will Venus assume its larger and more dramatic crescent phase.

    Mars (magnitude +1.3, in Leo) shines in the west after dusk to the upper left of Venus. Between Mars and Venus is Regulus, equal to Mars in brightness. In a telescope Mars is just a very tiny blob, 5.3 arcseconds in diameter.

    Jupiter on June 25, 2010
    Jupiter's Great Red Spot is still floating free in the absence of the South Equatorial Belt. Christopher Go took the bottom image at 20:32 UT June 25th, and the top image 24 minutes later. South is up.

    Jupiter (magnitude –2.4, in Pisces) rises around midnight or 1 a.m. daylight saving time and shines high in the southeast before dawn. It's the brightest starlike point in the morning sky. See our article on Jupiter's disappearing South Equatorial Belt.

    Jupiter's Great Red Spot is near System II longitude 150°. Assuming it stays there, here's a list of all the Great Red Spot's predicted transit times for the rest of 2010.

    Saturn (magnitude +1.1, in the head of Virgo) is in the west-southwest during evening, to the upper left of Mars. The diagonal line of Saturn, Mars, Regulus, and Venus is shrinking; the three planets will bunch up low in the sunset in early August. A telescope shows Saturn's rings a mere 2° from edge-on.

    Uranus (magnitude 5.8, in Pisces) is about 2° from Jupiter. In a telescope Uranus is only 3.6 arcseconds wide compared to Jupiter's 41″.

    Neptune (magnitude 7.9, at the Aquarius-Capricornus border) is in good view during early morning hours well to Jupiter's west. See our finder charts for Uranus and Neptune in 2010.

    Pluto (magnitude 14, in northwestern Sagittarius) is high in the south-southeast by 11 or midnight. See our big Pluto finder charts for 2010.

    All descriptions that relate to your horizon or zenith — including the words up, down, right, and left — are written for the world's mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America. Eastern Daylight Time (EDT) equals Universal Time (also known as UT, UTC, or GMT) minus 4 hours.

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